This section provides background information related to the present disclosure, which is not necessarily prior art.
Liquid fuel such as gasoline stored in a vehicle fuel tank (e.g., fuel tank of an automobile) may be vaporized and remain in the fuel tank as evaporative fuel. The evaporative fuel may be supplied to an intake manifold of an internal combustion engine through an evaporative fuel processing system.
The vehicle, or rather systems of the vehicle, may check for leaks in the evaporative fuel processing system after stopping the engine. That is, the vehicle systems may determine whether there are evaporative fuel leaks in the evaporative fuel processing system after turning the engine off.
After stopping the engine, valves of the evaporative fuel processing system are closed to form a closed circuit and leaks of evaporative fuel from the evaporative fuel processing system are determined on the basis of changing pressure gradients.
There are strict emission standards and regulations for evaporative fuel leaks from the fuel tank. As such, vehicles may employ various technologies to determine evaporative fuel leaks as quickly as possible.
Existing evaporative fuel leak check systems, however, may have difficulties in determining evaporative fuel leaks in vehicles with downsized engines, hybrid vehicles, vehicles with start-stop engine systems to limit engine idling, and vehicles with other fuel saving technologies, and thus, are subject to improvement.